Circuit board connector



Nov. 16, 1965 E. F. sANlsLo CIRCUIT BOARD CONNECTOR 4 Sheets-Sheet 1Filed Nov. 9. 1961 Nov. 16, 1965 E. F. sANlsLo 3,218,603

CIRCUIT BOARD CONNECTOR Filed Nov. 9, 1961 4 Sheets-Sheet 2 FIGBINVENToR. lf2/GENE SANzsLo ATTOR Y Nov. 16, 1965 E. F. sANlsLo CIRCUITBOARD CONNECTOR 4 Sheets-Sheet 3 Filed Nov, 9. 1961 INVENTOR. EIGENE[Sams By/ AT ToRN Y Nov. 16, 1965 E. F. sANlsLo 3,218,603

CIRCUIT BOARD CONNECTOR Filed Nov. 9. 1961 4 Sheets-Sheet 4 INVENToR.fuer/vf FSArws Lo TORNEY United States Patent Otlce Patented Nov. 16,1965 3,218,603 CIRCUIT BDARD CONNECTOR Eugene F. Sanislo, Norwalk,Conn., assignor to Burndy Corporation, a corporation of New York FiledNov. 9, 1951, Ser. No. 151,237 2 Claims. (Cl. 339-176) This inventionrelates to electrical connectors and, more particularly, to electricalconnectors for cards or boards having electrical components andcircuitry thereon.

Circuit board connectors are Well known in the prior art. The boardshave a plurality of spaced apart, parallel contact surfaces which areengaged by a plurality of mating, spaced-apart, parallel resilientcontacts. These contacts are usually permanently mounted in theconnector insulating body, and conductors are usually permanentlyconnected thereto. Replacement of an individual contact is diicult, ifnot impossible.

The portion of the connector Contact which electrically engages theboard contact surface is customarily formed in a resilient configurationto provide at least a minimum mechanical pressure on the board contactsurface by the connector and thus to assure an adequate electricalconnection therebetween. Too little pressure may permit an intermittent,noisy, or high voltage drop connection. This is of particularsignificance when Very low energy circuits or dry circuits operating atmicro-volt and microampere levels are to be connected. This mechanicalpressure is applied by each connector contact regardless of whether aconductor is connected to the contact or not. The Wear resulting fromthis pressure on the board contact surface and the connector contact isthus effected each time the board is inserted into or removed from theconnector.

As a result of the current trend to miniaturization, it is necessary toprovide a maximum of connector contacts in a minimum of both totalvolume and especially linear measure along the length of the leadingedge of the board. Thus the connector contacts must be as small aspossible and the spacing between adjacent contacts must be a minimum.Yet each contact must be accurately located so that it will adequatelyengage but one board contact surface `and no others. The fabrication andassembly of an optimum connector is exceedingly diicult.

It is, therefore, an object of this invention to provide a connectorwherein both before and after a board is inserted into the connectoreach contact is individually insertable and removable from saidconnector, and wherein a plurality of conductors may be individuallyconnected to and disconnected from an individual contact, therebypermitting the ready replacement or rearrangement of contacts andconductors.

Another object is to provide a connector wherein a connector contact towhich no conductor is connected applies but a minimum pressure to theassociated board contact surface; while a connector contact to which aconductor is connected applies a higher pressure, thereby reducing thewear caused by nonconnected contacts, yet providing adequate pressure byconnected contacts.

A further object is to provide a connector wherein all conductors may beconcurrently connected to their contacts after the circuit board hasbeen inserted into the connector, and disconnected before the board isremoved, thereby minimizing wear on all the board contact surfaces.

Still another object is to provide a connector of miniature design whichcan be economically fabricated and assembled.

These and other objects and features of this invention will become moreapparent by reference to the following description taken in conjunctionwithvthe accompanying drawings, in which:

FIG. 1 is a partial front View of a connector embodying this invention;

FIG. 2 is a side view in section taken along line 2 2 of FIG. 1 showingthe connector with circuit board and wire terminations installed;

FIG. 3 is a side View in section taken along line A-A of FIG. 1 showingthe connector with its contact spring and without either a circuit boardor Wire terminations installed;

FIG. 4 is a side view in section taken along line 2-2 of FIG. 1 with acircuit board installed but showing a wire termination being insertedand a wire termination being extracted;

FIG. 5 is a side view in section taken along line A-A of FIG. l showingonly the connector body;

FIG. 6 is a side view in section taken along line B-B of FIG. l showingonly the connector body; and

FIG. 7 is a side view of a polarizing key for use with the connector ofFIG. l.

FIG. 8 is a side view of the polarizing key of FIG. 7 assembled to theconnector body.

Referring to the drawings, it Will be seen that the connector 11comprises a substantially rectangular solid shaped body 13 made ofsuitable insulating material, such as diallyl phthalate; a plurality ofspring contacts 15 which may be bent up from round wire stock of asuitable conductive, yet resilient material, such as heat treatedberyllium copper; and a plurality of conductor or Wire terminations 17Which may be bent into an L-shaped cross-section from stamped ilat stockof a suitable conductive and rigid material, such as cartridge brass.

The connector body has a plurality of closely spaced apart verticalbores 19 therethrough, from its front, circuit board receiving face 21,to its rear, wire termination-receiving face 23. The bores aresubstantially rectangular in cross-section although several projectionsare formed onto the side walls thereof to constrict the bore. Into thesebores 19 are inserted the contact springs 15. As shown in FIGURES 5 and6, each bore has a right side wall 25, a left side Wall 27, a top wall29 and a bottom wall 31.

A horizontal slot 33 is formed into the front face of the connector bodyand extends partially into all the vertical bores 19. The horizontalslot 33 is adapted to receive the circuit board 35.

Suitable mounting means, not shown, may be provided for the connectorbody, such as a pair of flanges on its ends which include holes formounting bolts.

Circuit boards customarily have a plurality of spacedapart parallel,contact strips or surfaces 37, as shown in FIGURE 2, adjacent andperpendicular to the leading edge of the board which is inserted intothe connector. These contact surfaces may be on one or both sides of thecircuit board. It is desirable that the center-to-center spacing of theboard contact surfaces and the connector contacts be identical andcoincident.

The connector contact springs 15, best shown in FIG- URE 3, are formedin what is essentially a U shape with a medial rear portion 39. Each legportion 41 and 43 of the U extends by two reverse bends 45 and 47, and49 and 51 into a Z shaped inward-going portion having three be bowedslightly to provide a two-point contact surface 69 and 71, and 73 and 75to engage the card contact sur faces 37.

As was previously mentioned, a plurality of bore side wall projectionsare provided to constrict the bore 19. Continuous webs 77 and 79 areformed from the left sidewall 27 to the right sidewall 25 above andbelow the circuit board slot 33 to provide a closed entry which limitsthe` thickness of the board 35 which may be inserted into the slot 33.The rear surfaces 81 and 83 ofthe webs serve as front stops for thecontact spring and prevent overi'nsertion of the contact spring 15 intothe bore 19. The top and bottom walls 29 and 31, respectively, togetherwith the webs 77 and 79, provide recesses 84 and 86, respectively, inwhich the hooks 65 and 67 of the contact spring 15 are free to movevertically. A projection 85 extends horizontally from the verticalcenter of the right sidewall to constrict more than one half of thewidth of the bore 19. The front surface 87 of the projection 85 servesas a rear stop for the contact spring 15 by engaging the medial portion39 of the contact spring. Al

pair of projections 88 and 89 are also formed von the right side wall 25above and below the board slot 33, respectively. These projections serveto space the contact spring 15 away from the right sidewall. The rearface 91 of the projection 89 extends somewhat further to the rear of thebore 19, and the projection 89 is closer to the bottom wall 31 than isthe rear face 93 of the projection 88, which is further from the topwall 29. A similar, but reversed, pair of projections 95 and 97 areformed on the left sidewall. However, projection 95 differs fromprojection 97 by having a gradual or sloping rear cam surface 99 ratherthan an abrupt one. When the contact spring 15 is inserted into the bore19 from its rear face 23 to the right of the projection 95, the camsurface 99, which is forward of the projection surface 87, serves toshift the spring leftwards to the center of the bore as the springpasses forward of the projection 85. By these projections, the contactspring is snap-locked in the forward portion of the bore 19. As may bebest seen in FIGURE 3, the inner legs 57 and 63 of the Z project intothe board slot 33, and as seen in FIGURE 2, resiliently engage the boardcontact surfaces 37. The contact spring may be extracted by inserting asuitable tool, not shown, to deflect the medial portion 39 of the springaway from the surface 87 and then moving the spring towards the rear ofthe bore and out of the connector body.

Referring to FIGURES 4 and 1, it will be seen that the wire terminations17 are formed with an L-shaped cross section, web 103 being the shorterleg of the L and slightly less in width than the width of the bore 19.The thickness ofthe longer web 105 is made equal to or slightly lessthan the thickness of the projection 88 or 97 to aid in centering thespring 15 within the bore. The rear end of each wire termination 17 isformed with a pair of U-shaped cross sections which are crimped over andinto thewire 107; forward U section 109 grasps the bare wire 111 whilerearward U section 113 grasps the insulation of the wire. Both sectionsare crimped into an elliptical cross section to minimize the total widthof the wire plus termination. A forward portion 115 of the short web isstruck up slightly to provide a detent which will engage a shoulder 117or 119 provided in top and bottom walls of the bore, respectively. Asmay -be seen in FIGURE 4, the wire terminations 17 may be inserted intothe rear of the bore 19, short web 103 sliding between the top or bottombore wall 29 or 31 and the outer leg 53 or 59 of the contact springrespectively, until detent 115 snaps into place forward of shoulder 117or 119. The long web 105 pasess to the side of the contact spring andassists the several bore projections in centering the contact spring inthe bore. The' contact spring resiliently presses against the wiretermination, pressing it against the top or bottom wall of the bore, andalso maintains electrical connection with the spring. The release of thewire terminations is effected by disengaging the detent from the boreshoulder 117 or 119, as by a tool 121 slid between the termination andthe wall, and pulling the termination out of the bore, as by aprojection 123 on the tool engaging a shoulder 125 on the termination17. The wire termination may be inserted 4or extracted regardless ofwhether the board is inserted between the legs of the contact spring ornot. The insertion of the termination 17 is polarized with respect tothe bore 19 tothe vertical plane by the height of the longer web 105being greater than the width of the bore, and forwardly and rearwardlywithin the vertical plane by either the rear surface 91 of projection89, or the medial portion 39 of the Contact spring obstructing furtherinsertion of the narrow web 103, if the narrower web is centrallydirected with respect to the bore, rather than correctly outwardly.

It will be noted that the wire termination, when inserted, reduces thevertical distance available to the Z portion of the contact spring,thereby increasing its compression and thus the pressure it' will exerton the board contact surface 37. Thus, to achieve a high contactpressure and corresponding good electrical connection between thecontact spring inner leg '57 or 63 and the re spective card contactsurface 37, while providing, during; insertion and removal of the card,Va lower contact pressure and corresponding lower wear on the contactspring lleg and the card contact surface, it is merely necessary toinsert the wire termination after the board is inserted, and to extractthe terminations before the board is extracted. If desired, all of theWire terminations may be seized by a single tool, `or mounted on asingle back strip for concurrent insertion and extraction.

If desired, a polarizing key 127 such as is shown in FIGURE 7 may beutilized to block off individual bores in the connector. The key issubstantially of U shape, having a medial reverse bend 129, and a pairof upset detents 131 and 133 on legs 135 and 137, respectively. The keymay be inserted fromy the front of the connector, legs 135 and 137passing through and beyond the bore so that detents 131 and 133 snapbehind the rear surface of the connector body 13. If desired, shoulders,not shown, similar to shoulders 117 and 119 may be formed in the` topand bottom walls of the bore to receive detents 131 and 133. The widthof the key is equal to or less than the width of the bore. The key isadapted to c0- operate with a mating slot cut into the leading edge ofthe cards. The legs of the key, projecting slightly to the rear of theconnector, serve as an indication that no termination is to be insertedinto that specific bore.

The invention has thus been described but it is desired to be understoodthat it is not confined to the particular forms or usages shown anddescribed, the same being merely illustrative, and that the inventionmay be carried out in other ways without departing from the spirit ofthe invention, and therefore the right' is broadly claimed to employ allequivalent instrumentalities coming within the scope of the appendentclaims, and by means of which objects of this invention are attained andnew results accomplished, as it is obvious that the particularembodiments herein shown and described are only some of the many thatcan be employed to obtain these objects and accomplish these results.

I claim:

1. An electrical connector for a circuit board having a plurality ofside-by-side spaced-apart conductor surfaces disposed adjacent theleading edge of Vthe board, comprising: a connector body having aplurality of side-by-side spaced-apart channels extending therethroughand a transversely extending slot intersecting each of said channels forreceiving the leading edge of said board therein; a plurality of contactsprings each adapted to be inserted into one of said channels and eachhaving a contact surface for resiliently engaging and applying a givenpressure to a conductor surface on a circuit board inserted into saidslot, wherein .a portion of each contact spring is resilientlycompressed between a Wall of said channel and a conductor surface uponinsertion of said circuit board; a plurality of insertable and removablewire termination members adapted to be inserted into the channels toelectrically engage the contact springs therein for completingelectrical paths between said circuit board conductor surfaces andexternal wire conductors, through said springs, each of said terminationmembers being disposed between the wall of said channel and thecorresponding contact spring to increase the compression of said spring.

2. The electrical connector of claim 1 wherein said channel wallincludes a shoulder, and said Wire termination member includes a detentportion adapted to engage said shoulder to retain said terminationmember within 6 said channel such that said detent may be disengaged byfurther compressing said spring portion.

References Cited by the Examiner UNITED STATES PATENTS 2,457,703 12/1948Merkel 339-150 2,640,970 6/1953 Falge et al. 339-217 X 2,793,354 5/1957Heimbach 339-198 2,911,612 11/1959 Jackson et al. 339-176 2,983,8965/1961 Gilbert 339-176 X 3,024,436 3/1962 Kirk 339-176 3,047,831 7/1962Majewski 339-176 3,047,832 7/1962 Deakin 339-217 3,048,811 8/1962 Lock339-176 JOSEPH D. SEERS, Primary Examiner.

ALFRED S. TRASK, Examiner.

1. AN ELECTRICAL CONNECTOR FOR A CIRCUIT BOARD HAVING A PLURALITY OFSIDE-BY-SIDE SPACED-APART CONDUCTOR SURFACES DISPOSED ADJACENT THELEADING EDGE OF THE BOARD, COMPRISING: A CONNECTOR BODY HAVING APLURALITY OF SIDE-BY-SIDE SPACED-APART CHANNELS EXTENDING THERETHROUGHAND A TRANSVERSELY EXTENDING SLOT INTERSECTING EACH OF SAID CHANNELS FORRECEIVING THE LEADING EDGE OF SAID BOARD THEREIN; A PLURALITY OF CONTACTSPRINGS EACH ADAPTED TO BE INSERTED INTO ONE OF SAID CHANNELS AND EACHHAVING A CONTACT SURFACE FOR RESILIENTLY ENGAGING AND APPLYING A GIVENPRESSURE TO A CONDUCTOR SURFACE ON A CIRCUIT BOARD INSERTED INTO SAIDSLOT, WHEREIN A PORTION OF EACH CONTACT SPRING IS RESILIENTLY COMPRESSEDBETWEEN A WALL OF SAID CHANNEL AND A CONDUCTOR SURFACE UPON INSERTION OFSAID CIRCUIT BOAR; A PLURALITY OF INSERTABLE AND REMOVABLE WIRETERMINATION MEMBERS ADAPTED TO BE INSERTED INTO THE CHANNELS TOELECTRICALLY ENGAGE THE CONTACT SPRINGS THEREIN FOR COMPLETINGELECTRICAL PATHS BETWEEN SAID CIRCUIT BOARD CONDUCTOR SURFACES ANDEXTERNAL WIRE CONDUCTORS, THROUGH SAID SPRINGS, EACH OF SAID TERMINATIONMEMBERS BEING DISPOSED BETWEEN THE WALL OF SAID CHANNEL AND THECORRESPONDING CONTACT SPRING TO INCREASE THE COMPRESSION OF SAID SPRING.